<p>I think the essays must carry a decent amount of weight, because they are actual performance by the applicants, not other peoples’ characterization of performance (grades, recommendations), or objective ratings that fail to make meaningful distinctions among serious candidates (test scores). Not that those aren’t important, too, but essays are the thing itself, not second-hand accounts, and that’s powerful. (I also think that, rightly or wrongly, admissions people believe they can sniff out essays that have been “helped” too much.)</p>
<p>Essays are probably treated somewhat differently for students who look like humanities or social science types and for those who look like hard scientists/engineers. For the former, a pedestrian essay may be a near-killer. Why take someone who can’t write when there are so many people who can? For the latter, the hurdle is probably lower. Functional may be OK, but great would be a big plus.</p>